Gravity operated locking hinge

ABSTRACT

A hinge provided with a first part and a second part, which parts are able to turn relative to one another from a first position of the hinge into a second position of the hinge, the hinge being provided with a locking element for locking the hinge in the first position thereof, which locking element can move between a first position for releasing the hinge and a second position for locking the hinge. A locking element is fitted in a movable manner for moving under the influence of gravity, between the first position and the second position when the hinge sways.

BACKGROUND OF THE INVENTION

The invention relates to a hinge provided with a first part and a secondpart, which parts are able to turn relative to one another from a firstposition of the hinge into a second position of the hinge, the hingebeing provided with a locking element for locking the hinge in the firstposition thereof, which locking element can move between a firstposition for releasing the hinge and a second position for locking thehinge.

The hinge according to the present invention is in particular suitableas an orthopedic knee joint. Orthopedic knee joints are, for example,used by patients who are not capable of stabilising the knee jointwithout aids. Without aids, the knees of such patients would give waywhen they walk. When walking, the leg moves from the point in time thatthe heel makes contact with the ground from a position in which it isstretched forward into the so-called mid-position stage in which the legis essentially perpendicular under the body. Because the body is movingforward relative to the leg, the leg will then be pointing somewhatbackwards with respect to the body. The leg then returns via theso-called swinging stage back to the initial position in which the heelmakes contact with the ground.

For paralysis patients, for example, in order to be able to walk safelyit is necessary that an orthopedic knee joint stabilises the patient'sknee at the end of the standing stage, but in any event from the pointin time when the heel of the foot comes into contact with the ground toat least the mid-position stage. The simplest solution for achievingthis is to make use of an orthesis that fixes the thigh relative to thelower leg when walking. This can be effected, for example, by means of ahinge that is locked while walking. At the point in time when a usersits down, the user can unlock the hinge in order to make it possible tobend the leg. A significant disadvantage of a hinge of such simpleconstruction is that the user has to walk with a stiff leg. The ease ofuse of orthopedic knee joints is appreciably improved if the orthopedicknee joint is automatically unlocked when the swinging stage starts.With automatic unlocking of the hinge, a user is able to walk in anormal manner. At the point in time when the leg is placed on theground, the knee is stabilised with the aid of the orthopedic kneejoint, so that the user can bear safely on the locked knee. The hinge isunlocked at the point in time when the swinging stage has to start. Thiscan take place safely because the weight of the user has then beentransferred to the other leg.

Orthopedic knee joints with which the joint can be unlocked at the startof the swinging stage are known in the state of the art. U.S. Pat. Nos.5,490,831 and 2,943,622 and European Patent Application EP 0 872 224disclose knee joints with which the presence of stress on a user's heelis used as a signal for locking the knee joint. According to thesepublications a detection element is present in the heel, which detectionelement is, for example, connected by a cable or rod to a lockingelement. As long as the detection element detects that stress is beingexerted on the heel, the joint is locked by means of the lockingelement. However, as soon as there is no longer any stress on the heel,the knee joint is released. A significant disadvantage of the solutionaccording to the said documents is that the knee joint will also beunlocked if stress is exerted on, for example, the front of the user'sfoot. If the user is negotiating an obstacle, such as, for example, akerb, with his/her leg, the detection element will not detect any stresson the heel and will release the hinged joint. The user's knee jointwill consequently give way. As a result of this limitation, the solutionaccording to the abovementioned documents is impractical and, moreover,dangerous. An alternative solution for providing automatic unlocking ofthe joint is disclosed in U.S. Pat. No. 3,826,251. According to this USPatent the presence of an axial force on the hinge is used to eitherlock or release the hinge. A significant disadvantage of this solutionis that the bulk of the reactive force from the ground is absorbed bythe leg. That is to say this reactive force is not absorbed by the hingeand can also be not be detected by the hinge. This means that thesehinges do not work well in practice.

U.S. Pat. No. 4,632,096 discloses a hinge that can be released byturning the foot relative to the leg. A cable is attached to the foot,which cable is connected to a locking element in the knee joint. Byturning the foot, locking of the hinge can be released with the aid ofthe cable.

The disadvantage of the solution according to this US Patent is thatunlocking can take place only by active turning of the foot. This meansthat the user must be prepared to turn his/her foot at every step.Furthermore, in this solution a coupling is always needed between theknee joint and the foot or the ankle joint. This makes the systemsusceptible to malfunctions and in the majority of cases the aid inwhich the knee joint is incorporated will have to be equipped with afoot section. Moreover, here again the functioning of the system isdependent on the ground surface.

SUMMARY OF THE INVENTION

In view of the abovementioned disadvantages of the solutions accordingto the prior art, the aim of the present invention is to provide a hingeof the abovementioned type, and in particular an orthopedic knee jointthat is provided with a hinge of the type mentioned in the preamble,wherein the hinge is provided with a construction such that locking andrelease of the hinge takes place automatically while walking, withoutthe user actively having to deactivate the locking.

Said aim is achieved according to the present invention in that alocking element is fitted in a movable manner for moving under theinfluence of gravity between the first position and the second positionwhen the hinge sways.

If the hinge according to the present invention is used as an orthopedicknee joint, the hinge as a whole will sway with respect to the verticalduring use. During swaying of the hinge, the locking element will bemoved under the influence of gravity between, respectively, the firstposition for releasing the hinge and the second position for locking thehinge.

When the hinge is used in an orthopedic knee joint, the hinge is movedinto the first position in the swinging stage. In order for the hinge tofunction well, it is necessary that the hinge is then locked with theaid of the locking element. This means that the locking element musthave been brought into the second position at least by the end of theswinging stage. The user will then exert stress on the leg, and thus onthe hinge. Because the hinge is locked with the aid of the lockingelement, the user is able to walk safely. Because the hinge will swaywith respect to the vertical during the walking movement, it is possiblefor the locking element to be moved into the first position under theinfluence of gravity, in order to release the hinge, just before a newswinging stage starts. This movement of the locking element into thefirst position thereof takes place under the influence of gravity andthus occurs automatically. The user does not have to take any furthermeasures in order to move the locking element. Because the lockingelement is in the first position, the locking element will release thehinge and it is possible to move the first part of the hinge relative tothe second part. That is to say, the user's thigh is able to pivot withrespect to the lower leg. As a result a user is able to bend his/herknee in a normal manner and to walk in a normal manner. As a result ofthe swinging stage, the hinge returns to the first position thereof, thehinge again being locked in the first position with the aid of thelocking element.

For the sake of clarity it is pointed out that in the present inventionspecific reference is made to the use of the hinge according to theinvention in an orthopedic knee joint. It is clear that the hingeaccording to the present invention is also suitable for other joints,such as, for example, an orthopedic elbow joint, an ankle joint or a hipjoint. The present invention is therefore explicitly not restricted toorthopedic knee joints.

According to the invention it is advantageous that when the hinge is inthe first position the second part is essentially in the extension ofthe first part, the second part being at an angle with respect to thefirst part when the hinge is in the second position.

In order to be able to use the hinge according to the invention as anorthopedic knee joint it is necessary to connect elements for couplingthe knee joint to the user's leg or leg prosthesis to the first part andthe second part of the joint. In use, it is advantageous that the firstpart and the second part are essentially in line in the first positionof the hinge with this arrangement.

According to the invention it is advantageous that the locking elementis fixed in the hinge in such a way that it is able to turn or slide,the locking element being able to move or pivot about the axis ofrotation thereof under the influence of gravity.

The locking element can be fitted in the hinge in various ways. Byfixing the locking element such that it can turn, the position of thelocking element is unambiguously defined at all times. Furthermore, theconstruction is relatively simple.

What is achieved as a result of this measure is that the locking elementhas two stable end positions. Depending on the position of the hinge,the locking element will be moved into either the first position thereofor the second position thereof.

According to the invention, it is furthermore advantageous that thecenter of gravity of the locking element is some distance away from theaxis of rotation of the locking element.

It is furthermore advantageous that the center of gravity of the lockingelement is located above the axis of rotation of the locking elementwhen the hinge is in the use position.

In order to increase the force with which the locking element locks thejoint it is furthermore possible that the second part is provided with aprojection, which projection describes a path when the second partpivots relative to the first part, the locking element allowing theprojection a free movement path when it is in the first position thereofand being present in the movement path of the projection when it is inthe second position thereof.

It is pointed out that mechanical reversal, that is to say theprojection is fixed to the first part instead of to the second part, isalso possible. What is achieved by making use of a projection thatdescribes a path and moving the locking element respectively into or outof the path is that the locking element can be arranged some distanceaway from the axis of rotation of the first part of the hinge relativeto the second part of the hinge.

According to the invention it is furthermore advantageous that the hingeis provided with a first and a second stop in order to limit themovement of the locking element in, respectively, the first and thesecond position thereof.

The presence of these stops ensures that the maximum stroke of thelocking element from, respectively, the first position into the secondposition thereof is restricted, so that what is achieved is that thelocking element indeed moves at the point in time when the hinge isswayed with respect to the vertical.

According to the invention it is advantageous that the hinge is providedwith a displacement mechanism for forcing the locking element into,respectively, the first or the second position thereof.

In this context it is advantageous that the displacement mechanismcomprises a control element that can be operated by hand.

In practice, situations are conceivable where a user will him/herselfwant to be able to exert influence on whether or not the hinge in a kneejoint is unlocked or locked. This is the case, for example, when a userwants to sit down. In this context it is advantageous if the user has,for example, a control element that can be operated by hand in order tomove the locking element from the second position, in which the hinge islocked, into the first position of the locking element, in which thelocking element releases the hinge.

The opposite case is also conceivable. In this case the user wants, forexample, to lock the hinge when the user takes a step backwards. Forboth of these applications it is advantageous if the user is able, forexample, to change the position of a pawl by hand, which pawl isconnected to the locking element with the aid of a cable or anothermechanism.

According to the invention it is advantageous that the first and thesecond stop are arranged on a disc, it being possible to rotate or tomove the disc with the aid of the displacement mechanism in order toforce the locking element into, respectively, the first or the secondposition thereof.

The disc with the stops thereon is, for example, arranged in the hingein such a way that the axis of rotation of the disc is coincident withthe axis of rotation of the locking element. By this means, by rotatingthe disc with respect to the axis of rotation the extreme positions ofthe stops for limiting the locking element in both the first and thesecond position thereof are changed at the same time. By rotating thedisc in a first direction the locking element can be so moved, with theaid of the stops, that it always releases the hinge. By rotating thedisc in the opposing direction the locking element is so manipulated bythe stops that it locks the hinge at all times.

According to the invention it is furthermore advantageous that thelocking element is constructed as a body for transmitting forces fromthe second part via the locking element to the first part.

As a result of this measure, forces which are exerted on the first partare transmitted via the locking element to the second part. In order toprevent the pivot pin of the locking element being subjected toexcessive stress as a result of the transmission of the forces from thefirst part to the second part, it is advantageous that the lockingelement is connected to the pivot pin thereof via a flexible element,such as a rubber ring.

According to the invention, it is furthermore advantageous that thelocking element is provided with an adjusting body for adjusting thecenter of gravity of the locking element with respect to the axis ofrotation thereof.

It is possible to adjust the hinge with the aid of the adjusting body.The user can him- or herself, according to need, select the point intime at which the locking element swings under the influence of gravityfrom the first position into the second position thereof.

The invention further relates to an orthesis provided with a first partthat is provided with means for attaching the first part to a first partof the body or replacement body part and a second part that is providedwith means for attaching the second part to a second part of the body orreplacement body part. The particular feature of the orthesis accordingto the invention is that this is provided with a hinge according to theinvention.

As already indicated above, the hinge according to the present inventionis in particular suitable for use in an orthopedic knee joint.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further explained with reference to the appendedfigures, in which:

FIG. 1 shows a view of the hinge according to the invention incorporatedin an orthopedic leg orthesis.

FIG. 2 shows a detail of an exposed view of a hinge according to theinvention in the first position thereof, in which the locking elementlocks the hinge.

FIG. 3 shows an exposed view of the hinge according to the invention inthe second position thereof, in which the locking element releases thehinge.

FIG. 4 shows a perspective view of the first part of the hinge accordingto the invention from a first side.

FIG. 5 shows the first part of the hinge according to the invention in aperspective view from the second side.

FIG. 6 shows the second part of the hinge according to the invention ina perspective view, seen from a first side.

FIG. 7 shows a second view of the second part according to FIG. 6.

In FIGS. 8, 9 and 10 the operating principle of a knee joint accordingto the invention is shown diagrammatically, a rotatable coupling elementbeing fitted in the hinge within a guide.

FIGS. 11, 12 and 13 show, diagrammatically, the principle of acorresponding knee joint, where the locking element is now provided witha pawl that can be accommodated in a guide slot.

FIGS. 14, 15 and 16 show, diagrammatically, a knee joint with apivotable locking element, the center of gravity of which is locatedabove the pivot pin.

FIGS. 17 and 18 show, diagrammatically, a further development of thejoint according to FIGS. 14, 15 and 16.

FIGS. 19, 20 and 21 show a joint as in FIGS. 14, 15 and 16, where use ismade of a lever, for enhancing the power, between the pivotable lockingelement and a blocking projection.

FIGS. 22, 23 and 24 and FIGS. 25, 26 and 27 show knee joints in whichthe position of the blocking mechanism is assisted by means of springtension.

FIGS. 28, 29 and 30 show an embodiment of a knee joint in two mutuallyperpendicular views and in a cross-section along the line XXX—XXX inFIG. 28.

FIGS. 31–33 show a further variant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the hinge 1 that is incorporated in an orthopedic kneejoint. The orthopedic knee joint is attached to one leg 2 of a user. Theorthopedic knee joint 1 comprises a first part 11 and a second part 12that are connected to one another such that they can turn. The firstpart 11 is provided with a bracket 13 on which a fixing element 14 ismounted. Said fixing element 14 is used to attach the orthopedic kneejoint to a user's thigh. In the same way, the second part 12 of thehinge 1 is provided with a bracket 15 on which a second fixing element16 is fixed for attaching the orthopedic knee joint to the user's lowerleg. In addition, a support 17, for supporting the user's foot, isfitted at the end of the bracket 15. The hinge 1 can be locked with theaid of a locking element. This is further explained with reference toFIGS. 2 and 3. During the walking movement of a user, this lockingelement can be moved from a first position for releasing the hinge 1into a second position for locking the hinge 1. When the hinge 1 islocked, the first part 11 is fixed with respect to the second part 12.That is to say, a user can safely place weight on the leg 2 in theknowledge that the knee is locked. At the point in time when the userhas moved his/her body so far that the leg 2 extends somewhat towardsthe rear with respect to the body, that is to say the end of the stagein which stress is placed on the leg 2, the locking element (see FIGS. 2and 3) will move into the first position thereof in order to release thehinge 1. That is to say from the point in time when the swinging phaseof the leg starts, the second part 12 is able to pivot with respect tothe first part 11. This is shown in broken lines in FIG. 1. By makinguse of the hinge 1 according to the present invention, a user who him-or herself is unable to stabilise his/her knee is able to walk normallyas if he/she had a normal leg.

Situations are conceivable in which the user him- or herself wants to beable to influence whether or not the hinge 1 is locked. The hinge 1according to the present invention is therefore provided with adisplacement mechanism such as control element 20 (FIG. 1) that can beoperated by hand. With the aid of this element 20, the locking elementin the hinge 1 can be deliberately moved into the first position inorder to release the hinge or into the second position in order to lockthe hinge. In this context consideration can be given, for example, to apoint in time when a user wants to sit down. In this case the user willwant to unlock the hinge him- or herself. If a user wants to placeweight on the leg, for example as he or she takes a step backwards, theuser can deliberately lock the knee with the aid of the control element20. The element 20 is, for example, connected to the first part 11 ofthe hinge 1 with the aid of a cable 21.

The hinge 1 according to the present invention is again shown in FIG. 2.In FIG. 2 the hinge 1 is shown in a somewhat exposed view so that theinterior of the hinge 1 can be seen. A locking element 30 fitted suchthat it can pivot. This locking element 30 is fixed to a pivot pin 31 sothat it can turn. The locking element 30 is fixed to the pivot pin 31with the aid of a flexible element, such as, for example, a rubber ring.The turning movement of the locking element 30 is limited by means of astop 32. This stop 32 is mounted on a disc 33. This disc 33 has the samepoint of rotation as the locking element 30. The extreme positions ofthe turning movements of the locking element 30 are determined by thepresence of the stop 32. Because the stop 32 is itself fixed to a disc33, the position of the stop 32 relative to the hinge 1 can be moved.The locking element 30 can be brought into the first or into the secondposition thereof by rotating the disc 33. According to FIG. 2, thelocking element 30 is in the second position. The locking element 30 isthen in the path of a projection 34 on the second part 12. This path isshown with the aid of a dotted line 35. When the hinge 1 is swayed inits entirety, the locking element 30 will be able to pivot in theanticlockwise direction under the influence of gravity. As a result thelocking element 30 comes into the first position thereof in order torelease a hinge. This situation is shown in FIG. 3. The hinge 1according to the invention is again shown in FIG. 3. According to FIG.3, the second part 12 has pivoted relative to the first part 11. This ispossible because the locking element 30 has now moved out of the path 35of the projection 34.

A perspective view of a possible embodiment of the first part 11according to the present invention is shown in FIGS. 4 and 5. A possibleembodiment of the second part 12 of the hinge according to the inventionis shown in FIGS. 6 and 7. As can be seen if FIGS. 4–7 are takentogether, the second part 12 extends at least partially through the bodyof the first part 11. With this arrangement the projection 34 on thesecond part 12 extends into the opening 37 that has been made in thebody of the first part 11.

The principle of a knee joint is shown diagrammatically in FIGS. 8, 9and 10, which joint comprises a upper part 101 that can be attached to auser's thigh via an extension piece, which is not shown, or via a pin.The upper part 101 is connected via hinge 102 to a lower part 103 thatcan be connected via an extension piece, which is not shown, to a user'slower leg or lower leg prosthesis. As has already been stated above, inorder to obtain a walking movement that is as natural as possible theupper part must be locked with respect to the lower part during thatpart of the walking movement in which the leg is pointing forwards; seeFIG. 8. This locking must be maintained until approximately themid-position, see FIG. 9, and thereafter the two parts must be unlockedduring the backward swing, so that the lower leg is able to swingbackwards, see FIG. 10. In this embodiment this is achieved by ablocking mechanism which comprises a cylinder or ball 200 that is ableto execute a rolling or sliding back-and-forth movement between twostable positions in guide 201. In the position in FIG. 8, a torque Fs—Fsis acting in the joint, the one force of which passes through the hinge102 and the other force of which passes through the cylinder/ball 200and projection 107, as a result of which the two parts are locked withrespect to one another. When the leg is swung backwards, just beyond themid-position, in FIG. 9, gravity forces the cylinder/ball into its otherstable position, as a result of which the upper and lower parts areunlocked so that, as shown in FIG. 10, the lower leg part is able topivot relative to the thigh part. The leg can now be bent. In this way aknee joint is obtained that makes a virtually natural walking movementpossible.

A variant of this embodiment is shown in FIGS. 31–33, with a blockingmechanism which comprises a pawl 104 that can be pivoted about a pin 105and on one side of pin 105 is coupled to a weight 106. On the other sidepawl 104 is provided with a projection 107 that is able to engage in arecess in the upper part. In the position in FIG. 31, a torque Fs—Fsacts on the leg, the one force of which passes through hinge 102 and theother force of which passes through projection 107. Gravity Fg acts onthe weight 106 along a line that is located a distance x to the right ofthe pin 105 of the pawl 104, so that a torque acting to the right isexerted on this pawl, which torque forces the projection 107 into therecess and thus locks upper and lower part with respect to one another.When the leg is swung backwards, the distance x becomes zero in themid-position, FIG. 32, and, when the leg is swung further backwards, xis to the left of the pin 105, as a result of which a torque acting tothe left is then exerted on pawl 104, as a result of which the pawlpivots to the left and the projection 107 disengages from the recess andupper and lower part are unlocked.

One problem that can arise with this embodiment is that the pawl 104,with pendulum weight 106 attached thereto, starts to oscillate freely atits natural frequency. The question then is whether the pawl will returnto the correct position at the correct point in time. In order toovercome this problem, in the embodiment according to FIGS. 11, 12 and13 the pawl 104, which is now pivotably attached to the upper part, isprovided with a projection 107 that in one position, FIG. 11, bears on asurface of the lower part to produce locking and in the unlockedposition is accommodated in a slot 108 in the lower part and is guidedin said slot. In this way the movement of the pawl 104 is controlled inboth positions.

Another embodiment of the joint is shown in FIGS. 14, 15 and 16, abi-stable element 114, which has a center of gravity 116 located abovethe pivot pin 115 thereof, now being used as locking element. When theleg is in the position according to FIG. 14, where the leg is pointingforwards, the center of gravity 116 is to the left of the pin 115, sothat the element has flipped over to the left and is in contact with afirst stop 118 and in that position locks upper and lower part to oneanother. When the leg is in the position according to FIG. 15, thecenter of gravity 116 is virtually above the pin 115, but still to theleft thereof, so that the joint is still locked. As the leg continues toswing, the center of gravity 116 will move to the right of the pivot pin115 and as a consequence the element 114 will flip over into its secondposition in FIG. 16, the element then bearing on a second stop 119 andthe two parts of the joint being unlocked. Free oscillation of theelement 114 will not be possible with this embodiment.

A further embodiment of the principle described above is also shown inFIGS. 17 and 18, identical components being indicated by the samereference numerals in these figures. The construction and mode ofoperation of this embodiment will be clear following the above. It isalso pointed out that the tilting moment of element 114 can beinfluenced by, for example, making a hole 216 in one side of theelement.

FIGS. 19, 20 and 21 show, diagrammatically, an embodiment of the jointin which the locking element 114 again has a center of gravity 116 thatis located above the pivot pin and thus will assume two positionsdepending on the position of the leg. In this case the element 114cooperates with a lever 124, so that the power of element 114 isenhanced and the projection 125 at the end of the lever 124 will beforcefully pushed into the recess in the other joint part.

FIGS. 22, 23 and 24 show the same embodiment of the joint as in FIGS.17, 18, except that the locking element 114 is now coupled via anextension spring 130 to a point 131 on the lower part 103 andspecifically is coupled in such a way that in the situation in FIG. 22the locking element 114 is in contact with stop 118, the two joint partsare locked and the extension spring 130 is not under strain. With thisarrangement, the element 114 is trapped between the two joint parts andshocks will have no influence on its position. In the situation in FIG.24, the two joint parts are unlocked and the extension spring 130 isstretched by bending of the lower leg, so that the element 114 is pulledtowards the curved surface of the lower part. Any shocks to the leg willnow not result in the element 114 switching to a different position.

FIGS. 25, 26, 27 also show an embodiment which has extension springs 130and 132 in order to ensure that shocks to the leg do not result in anyundesired change in position of the element 114. One difference comparedwith the embodiment according to the preceding figure is that theelement 114 now interacts with a lever 124 that is connected to a pawl133 which provides the final locking.

FIGS. 28, 29, 30 show an embodiment in two mutually perpendicular viewsand a cross-section along the line XXX—XXX. In this embodiment the twojoint parts 101 and 103 are again connected by hinge 102. A lockingelement 114 is once again mounted in a bearing, using a ball bearing135, on the upper part 101 such that it can pivot. The location of thecenter of gravity above the pivot pin 115 again ensures that the element114 is again able to assume two positions, in which it is then incontact with the stop 118 depending on the position of the leg. Withthis arrangement, in the one position the joint is again locked whilstin the other position the joint is unlocked. In order to ensure that theelement in the unlocked situation will not execute any undesiredmovement under the influence of shocks, with this embodiment as well aspring 136 is fitted that at one end is pulled by an auxiliary spring137 into contact with a projection 138 on the lower part 103 and at theother end engages by a part 139 into a recess 140 in the locking element114. In this way the effect of shocks on the position of the lockingelement is effectively and simply eliminated.

In order to prevent the pin 115 from being damaged when the joint is inthe locked position, as a result of the forces exerted thereon by thelower part, the ball bearing 135 is accommodated via an elastic layer,which is not shown, preferably in the form of an O-ring, in the bore inthe upper part. If forces are now exerted by the lower part 103 on theelement 114, the bearing 115 will, as a consequence of the elasticlayer, move to some extent in its bore until the other side of theelement is in contact with the surface of the upper part and the forcesare absorbed by this.

1. An orthopedic hinge, comprising: a first part provided with means forattaching the hinge to a first body part or replacement body part; asecond part provided with means for attaching the hinge to a second bodypart or replacement body part, the first part and the second part beingable to turn with respect to each other between a first position whereinthe second part is essentially an extension of the first part, and asecond position wherein the second part is at an angle with respect tothe first part; and a locking element that is movable between a lockingposition and a release position, the locking element locks the firstpart and the second part with respect to each other in the lockingposition, the locking element enables relative movement of the first andthe second part with respect to each other in the release position,wherein the lock element is fixed in the hinge in such a way that thelocking element is able to turn, the locking element being able to pivotabout the axis of rotation of the locking element under the influence ofgravity from the locking position to the release position.
 2. The hingeaccording to claim 1, wherein the center of gravity of the lockingelement is spaced apart from the axis of rotation of the lockingelement.
 3. The hinge according to claim 1, wherein the center ofgravity of the locking element is located above the axis of rotation ofthe locking element when the hinge is being used.
 4. An orthopedichinge, comprising: a first part provided with means for attaching thehinge to a first body part or replacement body part; a second partprovided with means for attaching the hinge to a second body part orreplacement body part, the first part and the second part being able toturn with respect to each other between a first position wherein thesecond part is essentially an extension of the first part, and a secondposition wherein the second part is at an angle with respect to thefirst part; and a locking element that is movable between a lockingposition and a release position, the locking element locks the firstpart and the second part with respect to each other in the lockingposition, the locking element enables relative movement of the first andthe second part with respect to each other in the release position,wherein the locking element is pivotable about a pivot axis between thelocking position and the release position, and the center of gravity ofthe pivotable locking element is spaced apart from the pivot axis, sothat the locking element is movable due to the influence of gravity. 5.The hinge according to claim 4, wherein the second part is provided witha projection, said projection describes a path when the second partpivots relative to the first part, the locking element allowing theprojection a free movement path when the locking element is in therelease position and being present in the movement path of theprojection when the locking element is in the locking position.
 6. Thehinge according to claim 4, wherein the hinge is provided with a firstand a second stop in order to limit the movement of the locking elementin, respectively, the release and the locking position.
 7. The hingeaccording to claim 6, wherein the hinge is provided with a displacementmechanism for forcing the locking element into, respectively, therelease or the locking position.
 8. The hinge according to claim 7,wherein the displacement mechanism comprises a control element that canbe operated by hand.
 9. The hinge according to claim 7, wherein thefirst and the second stop are arranged on a disc, it being possible torotate the disc with the aid of the displacement mechanism in order toforce the locking element into, respectively, the release or the lockingposition.
 10. The hinge according to claim 7, wherein the lockingelement is fixed in the hinge in such a way that it is able to slide,the locking element being able to move about the axis of rotation of thelocking element under the influence of gravity.
 11. The hinge accordingto claim 10, wherein the first and second stop are arranged on a disc,it being possible to move the disc with the aid of the displacementmechanism in order to force the locking element into, respectively, therelease or the locking position thereof.
 12. The hinge according toclaim 4, wherein the locking element is constructed as a body fortransmitting forces from the second part via the locking element to thefirst part.
 13. The hinge according to claim 12, wherein the lockingelement is connected to a pivot pin of the locking element via aflexible element.
 14. The hinge according to claim 4, wherein thelocking element is provided with an adjusting body for adjusting thecenter of gravity of the locking element with respect to the axis ofrotation of the locking element.
 15. An orthopedic orthesis or prothesiswherein the orthesis or prothesis is provided with a hinge according toclaim
 4. 16. The orthopedic hinge according to claim 4, wherein thelocking element is movable under the influence of gravity from thelocking position to the release position upon swaying the hinge in thefirst position of the first part and the second part from an essentiallyvertical plane in a direction corresponding to a leg swung in a backwarddirection.
 17. The orthopedic hinge according to claim 4, wherein thelocking element is movable under the influence of gravity from therelease position to the locking position upon swaying the hinge in thefirst position of the first part and the second part from an essentiallyvertical plane in a direction corresponding to a leg swung in a forwarddirection.
 18. The orthopedic hinge according to claim 4, wherein thecenter of gravity of the pivotable locking element in the lockingposition is on a first side of a vertical plane through the pivot axis,and wherein the center of gravity of the pivotable locking element inthe release position is on a second side of said vertical plane, saidsecond side is opposed to said first side.
 19. The orthopedic hingeaccording to claim 4, wherein during use, the center of gravity of thepivotable locking element is located above the pivot axis.
 20. Theorthopedic hinge according to claim 4, wherein the locking elementcomprises a bi-stable element.
 21. The orthopedic hinge according toclaim 4, wherein during use, the center of gravity of the pivotablelocking element is located below the pivot axis.
 22. The orthopedichinge according to claim 4, wherein the locking element comprises apendulum weight that is located below the pivot axis during use.
 23. Anorthopedic hinge, comprising: a first part connectable to a first bodypart; a second part connectable to a second body part different fromsaid first body part, said first and second parts being able to turnrelative to one another from a first hinge position to a second hingeposition; and a locking element for locking the hinge in the first hingeposition, said locking element being movable between a release positionfor releasing the hinge and a locking position for locking the hinge,said locking element being movable from the release position to thelocking position and from the locking position to the release positiondue to an influence of gravity, wherein the locking element is pivotableabout a pivot axis between the locking position and the releaseposition, and the center of gravity of the pivotable locking element isspaced apart from the pivot axis.